The companies hope to deliver robot-cooked meals or provide medical checkups using Toyota electric vehicles by the latter half the 2020s

TOKYO—SoftBank Group Corp. has teamed up with Toyota Motor Corp. to deliver meals, health care and other services in self-driving cars to an aging populace in Japan, in hopes that some of the technology will prove exportable.

The two companies said they would form a joint venture by the end of March, with 50.25% owned by SoftBank and 49.75% owned by Toyota, to deploy vehicles in a country where 83% of its bus operators aren’t profitable.